/*
 * Copyright 2002-2017 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.scripting.bsh;

import java.io.IOException;
import java.io.StringReader;
import java.util.Map;

import bsh.EvalError;
import bsh.Interpreter;

import org.springframework.beans.factory.BeanClassLoaderAware;
import org.springframework.lang.Nullable;
import org.springframework.scripting.ScriptCompilationException;
import org.springframework.scripting.ScriptEvaluator;
import org.springframework.scripting.ScriptSource;

/**
 * BeanShell-based implementation of Spring's {@link ScriptEvaluator} strategy interface.
 *
 * @author Juergen Hoeller
 * @see Interpreter#eval(String)
 * @since 4.0
 */
public class BshScriptEvaluator implements ScriptEvaluator, BeanClassLoaderAware {

    @Nullable
    private ClassLoader classLoader;


    /**
     * Construct a new BshScriptEvaluator.
     */
    public BshScriptEvaluator() {
    }

    /**
     * Construct a new BshScriptEvaluator.
     *
     * @param classLoader the ClassLoader to use for the {@link Interpreter}
     */
    public BshScriptEvaluator(ClassLoader classLoader) {
        this.classLoader = classLoader;
    }


    @Override
    public void setBeanClassLoader(ClassLoader classLoader) {
        this.classLoader = classLoader;
    }


    @Override
    @Nullable
    public Object evaluate(ScriptSource script) {
        return evaluate(script, null);
    }

    @Override
    @Nullable
    public Object evaluate(ScriptSource script, @Nullable Map<String, Object> arguments) {
        try {
            Interpreter interpreter = new Interpreter();
            interpreter.setClassLoader(this.classLoader);
            if (arguments != null) {
                for (Map.Entry<String, Object> entry : arguments.entrySet()) {
                    interpreter.set(entry.getKey(), entry.getValue());
                }
            }
            return interpreter.eval(new StringReader(script.getScriptAsString()));
        } catch (IOException ex) {
            throw new ScriptCompilationException(script, "Cannot access BeanShell script", ex);
        } catch (EvalError ex) {
            throw new ScriptCompilationException(script, ex);
        }
    }

}
